Calling all Sota fans.

Hi Lewn:
May I ask what turntable replaced the Dohmann in your friend's system?

Lewm the Chattanooga choo choo just rolled through…no problem but of course having a cement floor and cement pedestal doesn’t hurt 😎

My friend with the Doehmann sold it in favor of a major downsizing to his system, associated with moving to a smaller domicile.  He now uses hi-rez digital streaming exclusively.  Sold all his LPs, too, and gave me a few for free.  So in essence, nothing replaced the Doehmann.  This was a year or two ago.  Since then he bought a bigger house (now 40 miles away from me, in Baltimore) and seems to be sniffing around for a return to vinyl.  It's a long story, but I will respect his privacy.

Can't beat a cement floor; I agree, laid on bare earth.

@lewm , lewn, I like that :-)  It is Dohmann by the way not Doehmann.
Mark thinks that efficiencies in manufacture down in Australia will bring the price down enough that adding vacuum clamping and the dust cover will not add much. He is talking about $60,000, not chump change But, compared to other "ultimate" turntables, I could see myself doing this. There is no way I am going to buy an Air Force Zero. Mark has also become enamored with Schroder's LT arm and I believe he will be offering it with his tables. That arm is brilliant. It uses the friction of the stylus in the groove to drive the arm. 
A little hard to get back into it once you have sold all your records. 

jaym759, nice to hear from you again. I am glad you are enjoying your Cosmos. Donna has another customer who is thinking about putting a 4 Point 9 on a Cosmos. For some strange reason she wanted me to talk to him about it. He has an Origin Live arm which he was very unhappy with. Another story of poor customer support from Origin Live. Disappointing. They are not bad arms but this is the third or fourth sad example.

@chakster, A bargain? I would quantify it as financially irresponsible. IMHO, you have to be out of your mind to spend that much money on this antiquated format. But, what do I know. Unfortunately, I am just the type of silly person to do it.

Putting a straight line tracker on a suspended turntable is a bad idea. It will change it's level as the arm moves across the record. I have no idea how much but it will certainly change. 

I have no idea why. It is a 3 phase AC synchronous motor. Synchronous motors are best for turntables because they will automatically adjust torque to maintain the speed dictated by the AC signal they are given. It happens instantaneously. I suspect they are just miss-informed.

The SOTA motors are a BLDC type, also known as EC motors (electrically commutated).  These motors can be driven a number of ways.  They have 3 windings and hall sensors which can be used to signal the control circuitry when to commutate or switch the currents in the windings.  Only two of the 3 windings are driven at a time and the control circuitry can also change the polarity of the drive signal the same way a mechanical commutating ring changes current in a DC motor.  When driven this way, they behave very similar to DC motors where the DC current dictates the speed.  Without an external feedback loop, they will also exhibit poor speed stability, slowing down under load just as DC motors do. Besides poor speed stability, the motor can also exhibit increased vibration when driven this way.


If driven by 3 sinewaves, the motor behaves very similar to an AC synch motor where the frequency determines the motor speed rather than the drive level.  The drive level needs to be adjusted by the control circuitry as the speed changes to compensate for the change in back EMF in order to maintain torque and reduce vibration.  This is much more sophisticated than the simple block commutation controllers and is how the SOTA motors are driven.  It is rare to see this level of sophistication on tables under $20K.